Embodiments of the present disclosure relate to a flat panel sensor and a flat panel detector.
X-ray flat panel detectors play more and more important roles in the fields of medical imaging, material testing and inspection, airport or seaport security inspection, transportable battlefield use, and so on.
The structure of a conventional X-ray sensor of a flat-panel type is shown in FIG. 1(a). The conventional X-ray sensor comprises a plurality of pixel units that are arranged in an array, and each of the pixel units includes one photodiode 11 and one thin film transistor (TFT) 12. As for the TFT 12, its gate electrode is connected to a corresponding gate scan line 13 of the X-ray sensor, its drain electrode is connected to a corresponding data line 14 of the X-ray sensor, and its source electrode is connected to the photodiode 11. One terminal of the data line 14 is connected to a data drive circuit 15 via a connecting pin.
Through scan signals applied by a scan drive circuit 16, the conventional X-ray sensor controls the switching status of the TFTs 12. When the TFT 12 of one pixel unit is switched on, a photocurrent signal that is formed by the photodiode 11 sequentially passes through the data line 14, which are connected to the TFT 12, and the data drive circuit 15 and is read out. Acquisition of the photoelectric signals is accomplished by means of controlling the signal timings on the gate scan line 13 and the data line 14; namely, an operation that controls acquisition of the photocurrent signal formed by the photodiode 11 is accomplished by means of controlling the switching status of the corresponding TFT 12.
A cross-sectional view of one pixel unit in a conventional X-ray sensor of a bottom-gate type is shown in FIG. 1(b). The pixel unit includes: a base substrate 1, a gate electrode 2, a common electrode 3, a drain electrode 4, a source electrode 5, an active layer 6, a passivation layer 7, an indium tin oxide (ITO) layer 8, a gate protecting layer 9, and a planarization layer 10. The ITO layer 8 is connected to the source electrode 5 through a via hole. The formation of the via hole needs exposure, development and other processes, and moreover fabrication of two PVX layers is required, so that the process is complex and the cost is relatively high.